The archbishop of Canterbury, Justin Welby, lies on the ground at the Jallianwala Bagh memorial.
Photograph: Narinder Nanu/AFP/Getty Images

The archbishop of Canterbury has apologised “in the name of Christ” for the 1919 massacre at Amritsar in India, when hundreds of people were shot dead by British forces.

Prostrating himself at the memorial to the Jallianwala Bagh killings, Justin Welby said: “The souls of those who were killed or wounded, of the bereaved, cry out to us from these stones and warn us about power and the misuse of power.

“I cannot speak for the British government … but I can speak in the name of Christ and say this is a place of both sin and redemption, because you have remembered what they have done and their names will live, their memory will live before God. And I am so ashamed and sorry for the impact of this crime committed here.”

Hindus, Christians, Muslims and Sikhs were killed in April 1919 when they gathered in Amritsar, in Punjab, then part of British India. They were protesting peacefully after earlier riots over the arrest of pro-independence leaders.

Under the orders of Brig Gen Reginald Dyer, an Anglican, British troops opened fire. According to official figures, 379 people were killed and about 1,200 wounded, though other estimates suggested much higher casualties.

Winston Churchill condemned the massacre in the House of Commons, saying it was “an extraordinary event, a monstrous event, an event which stands in singular and sinister isolation”.

In 2013, David Cameron became the first serving prime minister to visit the site of the killings, bowing his head in honour of the victims. The episode was “deeply shameful” and should never be forgotten, he said, but he stopped short of apologising.

Writing on Facebook during a trip to Sri Lanka and India, Welby said visiting the memorial had aroused “a sense of profound shame at what happened in this place. It is one of a number of deep stains on British history.”

He added: “Learning of what happened, I recognise the sins of my British colonial history, the ideology that too often subjugated and dehumanised other races and cultures … We have a great responsibility to not just lament this horrific massacre but most importantly to learn from it in a way that changes our actions.”